Dimmer and on/off switch



FIG. 1 is a front left perspective view illustrating our new design for a dimmer and on/off switch;

FIG. 2 is a top view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational view thereof; and,

FIG. 6 is a bottom view thereof. 

The ornamental design for a dimmer and on/off switch, as shown and described. 